\psset{unit=1.4,algebraic}
\begin{pspicture*}(-1,-0.5)(2,2)
\psaxes[ticks=none,labels=none]{<->}(0,0)(-0.5,-0.5)(2,2)
\psplot[linecolor=blue]{0.4}{1.6}{x^1.5}
\footnotesize
\psxTick[ticksize=-3pt 0,labelsep=3pt](1){a}
\psyTick[ticksize=-3pt 0,labelsep=3pt](1){l}
\psline[linecolor=red,linestyle=dotted](1,0)(1,1)(0,1)
\uncover<2->{
\psyTick[ticksize=-3pt 0,labelsep=3pt](1.6565){l+\varepsilon}
\psyTick[ticksize=-3pt 0,labelsep=3pt](0.4648){l-\varepsilon}
}
\uncover<3->{
\psline[linecolor=red,linestyle=dashed](1.4,0)(1.4,1.6565)(0,1.6565)
\psline[linecolor=red,linestyle=dashed](0.6,0)(0.6,0.4648)(0,0.4648)
}
\uncover<4->{
\psxTick[ticksize=-3pt 0,labelsep=3pt](1.4){a+\delta}
\psxTick[ticksize=-3pt 0,labelsep=3pt](0.6){a-\delta}
}
\end{pspicture*}